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Debug mode option to error on evthread init AFTER other event calls.

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- A handy event_enable_debug_mode() feature which will error and abort the
  application if any thread-aware libevent functions are called BEFORE the
  evthread API has been initialized (manually, or through
  evthread_use_windows_threads() / evthread_use_pthreads()

- This is done by setting the global debug variable
  'event_debug_created_threadable_ctx_' whenever the following functions
  are called:

     evthreadimpl_lock_alloc_()
     evthreadimpl_cond_alloc_()
     event_base_new_with_config() <- this checks to see if the thread
                                     callbacks are enabled first, so we
                                     have to manually set the variable.

- Example:

int main(int argc, char ** argv) {
    struct event_base * base;

    event_enable_debug_mode();

    base = event_base_new();

    evthread_use_pthreads();

    return 0;
}

When executed, the program will throw an error and exit:

[err] evthread initialization must be called BEFORE anything else!
This commit is contained in:
Mark Ellzey 2015-05-15 02:58:14 -07:00
parent 6c8cb5ef7e
commit dcfb19a27b
2 changed files with 49 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
event.c
View File

@ -199,6 +199,20 @@ eq_debug_entry(const struct event_debug_entry *a,
}
int event_debug_mode_on_ = 0;
/**
* @brief debug mode variable which is set for any function/structure that needs
* to be shared across threads (if thread support is enabled).
*
* When and if evthreads are initialized, this variable will be evaluated,
* and if set to something other than zero, this means the evthread setup
* functions were called out of order.
*
* See: "Locks and threading" in the documentation.
*/
int event_debug_created_threadable_ctx_ = 0;
/* Set if it's too late to enable event_debug_mode. */
static int event_debug_mode_too_late = 0;
#ifndef EVENT__DISABLE_THREAD_SUPPORT
@ -656,6 +670,8 @@ event_base_new_with_config(const struct event_config *cfg)
/* prepare for threading */
#ifndef EVENT__DISABLE_THREAD_SUPPORT
event_debug_created_threadable_ctx_ = 1;
if (EVTHREAD_LOCKING_ENABLED() &&
(!cfg || !(cfg->flags & EVENT_BASE_FLAG_NOLOCK))) {
int r;

33
evthread.c
View File

@ -45,6 +45,11 @@
#define GLOBAL static
#endif
#ifndef EVENT__DISABLE_DEBUG_MODE
extern int event_debug_created_threadable_ctx_;
extern int event_debug_mode_on_;
#endif
/* globals */
GLOBAL int evthread_lock_debugging_enabled_ = 0;
GLOBAL struct evthread_lock_callbacks evthread_lock_fns_ = {
@ -89,6 +94,14 @@ evthread_set_lock_callbacks(const struct evthread_lock_callbacks *cbs)
{
struct evthread_lock_callbacks *target = evthread_get_lock_callbacks();
#ifndef EVENT__DISABLE_DEBUG_MODE
if (event_debug_mode_on_) {
if (event_debug_created_threadable_ctx_) {
event_errx(1, "evthread initialization must be called BEFORE anything else!");
}
}
#endif
if (!cbs) {
if (target->alloc)
event_warnx("Trying to disable lock functions after "
@ -124,6 +137,14 @@ evthread_set_condition_callbacks(const struct evthread_condition_callbacks *cbs)
{
struct evthread_condition_callbacks *target = evthread_get_condition_callbacks();
#ifndef EVENT__DISABLE_DEBUG_MODE
if (event_debug_mode_on_) {
if (event_debug_created_threadable_ctx_) {
event_errx(1, "evthread initialization must be called BEFORE anything else!");
}
}
#endif
if (!cbs) {
if (target->alloc_condition)
event_warnx("Trying to disable condition functions "
@ -406,6 +427,12 @@ evthreadimpl_get_id_()
void *
evthreadimpl_lock_alloc_(unsigned locktype)
{
#ifndef EVENT__DISABLE_DEBUG_MODE
if (event_debug_mode_on_) {
event_debug_created_threadable_ctx_ = 1;
}
#endif
return evthread_lock_fns_.alloc ?
evthread_lock_fns_.alloc(locktype) : NULL;
}
@ -434,6 +461,12 @@ evthreadimpl_lock_unlock_(unsigned mode, void *lock)
void *
evthreadimpl_cond_alloc_(unsigned condtype)
{
#ifndef EVENT__DISABLE_DEBUG_MODE
if (event_debug_mode_on_) {
event_debug_created_threadable_ctx_ = 1;
}
#endif
return evthread_cond_fns_.alloc_condition ?
evthread_cond_fns_.alloc_condition(condtype) : NULL;
}